Can anyone tell me if it's possible to fit a rear brake caliper from a later model ('01 onwards) the style of caliper which is hidden behind the swing arm, to an earlier 315 (the one with the brake caliper sat higher than the swingarm. I know they both locate of a pin on the inside of the swingarm, just wondered if they are interchangeable.

On some gas gas and sherco's it can be done but you have to alter the holding pin postition. On the early gas gas it is a threaded bolt so a drill and re tap then change the brake hose.

 

The older style calipers are still available and they work just as good or rebuild your existing one.